PHOENIX — Avery Bradley scored 23 points, Thomas burned his former team with eight critical points in the last two minutes, and the Boston Celtics held off the Phoenix Suns 115-110 Monday night.

Boston made a season-high 14 3-pointers, 10 in the first half as the Celtics ran out to a 19-point lead against the struggling Suns. But Phoenix cut the lead to one on a 3 from Eric Bledsoe with 2:33 remaining.

Thomas, just four days removed from his deadline-day trade to Boston, scored 21 points in his return.

Bledsoe had 21 points and 10 assists in the Suns’ eighth loss in the past nine games. Brandon Knight, acquired in another Suns deal last Thursday, had 20 in his first start for his new team.

Thomas entered the game with five minutes to go in the first quarter to cheers from the crowd. He scored 10 points in a second quarter that saw the Celtics score 41, and his four-point play with 1:37 left was the key moment of the game.

Thomas glared at the Suns’ bench after the 3-pointer and foul that raised Boston’s lead to five. His layup with 40 seconds gave the Celtics a 107-100 lead, and after that basket he smiled at his former teammates.

The Celtics tied a season high for points in a first half with 67, but didn’t shoot as well in the second half. Brandon Bass chipped in 18 points.

The Suns have free-fallen out of the eighth playoff seed in the West with five straight defeats.

The Celtics led by as many as 10 points in the first quarter, with Bradley scoring 14. Gerald Wallace, Jae Crowder, Thomas and James Young hit 3s in the second to give Boston a 55-37 lead.

Phoenix rallied in the third quarter after Evan Turner’s dunk gave the Celtics a 75-55 lead, going on a 16-2 run to cut the deficit to six. But Boston responded and took an 89-79 lead into the fourth quarter.